Recent tests for roof strength show that automakers are quickly improving the rollover safety, according to the Insurance Institute for Highway Safety.
The insurance institute, which is funded by the insurance industry, tested two large luxury cars and four midsize sport-utility vehicles. The institute rates on a scale of Good, Acceptable, Marginal and Poor. In cases where vehicles haven’t changed, the ratings can apply to earlier models.
The two large luxury vehicles, the 2011 Cadillac CTS and the 2011 Infiniti M, earned the top rating of Good in the tests that measure how well vehicles would protect people in rollover crashes. Both were redesigned for the 2011 model year. The new 2011 Ford Fiesta further illustrates this point. It is the only small car to get a Good rating. Earlier tested vehicles are all 2010 models. The Honda Fit, Hyundai Accent, Kia Rio, Mini Cooper and Toyota Yaris got an Acceptable and the Chevrolet Aveo got a Marginal.
In the midsize SUV tests, the 2010 Nissan Xterra, Toyota FJ Cruiser and Toyota 4Runner earned ratings of Acceptable. The 2010 Nissan Pathfinder was rated Marginal. These midsize sport-utility vehicles mostly represent older designs with roofs that haven’t been redesigned yet, according to the institute. The large luxury cars and midsize SUVs join others in their segments that have been tested earlier this year.
In the large luxury segment, the following vehicles earned a Good rating: The 2011 BMW 5 Series, 2010 Hyundai Genesis models manufactured after Jan. 2010; 2011 Lincoln MKS, 2010-2011 Mercedes E-Class, and 2010 Volvo S80. Getting an Acceptable rating were the 2010 Audi A6 and the 2011 Lexus GS. The 2010 Acura RL was rated Marginal.
Midsize SUVS tested earlier this year received the following rollover safety ratings.
Good: 2010-11 Chevrolet Equinox (twin GMC Terrain) built after March 2010; 2010-11 Ford Flex models built after January 2010; 2010 Jeep Liberty (twin Dodge Nitro), 2010 Toyota Highlander and Venza, plus the 2011 Jeep Grand Cherokee and Kia Sorento. The 2011 Ford Edge is rated Acceptable.
Midsize SUVs rated Marginal were the 2010 Honda Accord Crosstour, 2011 Honda Pilot, 2010 Mazda CX-7, 2011 Mitsubishi Endeavor, and 2010 Nissan Murano.
The Institute evaluates rollover protection using a roof strength test. In this test a metal plate is pushed against one corner of a vehicle’s roof at a constant speed. The maximum force sustained by the roof before 5 inches of crush is compared to the vehicle’s weight to find the strength-to-weight ratio. This is a good assessment of vehicle structural protection in rollover crashes.
Roofs of Good-rated vehicles can withstand a force equal to at least four times the vehicle’s weight. To receive an Acceptable, the roof must withstand a force equal to at least 3.25 times the vehicle’s weight. A Marginal rating is 2.5. Anything lower gets a Poor.
The insurance institute began evaluating roof strength in 2009 to compare the crashworthiness of vehicles in rollovers. The insurance institute’s test is more severe than the one conducted by the federal government, which requires most vehicles (those weighing up to 6,000 pounds), to withstand a force equal to 1.5 times the vehicle’s weight. It exempts heavier vehicles up to 10,000 pounds from the tests.
A new federal standard will begin to be phased in starting in September 2012 and it must be completed with 2017 model-year vehicles. The new standard requires vehicles that weigh up to 6,000 pounds to withstand a force equal to three times the vehicle’s weight. And the heavier vehicles have to meet a standard for the first time, which is 1.5 times the weight of the vehicle. And the new standard requires that the metal plate must push down on each side of the roof, not just one side. More information is available at www.iihs.org. — Cheryl Jensen, Motor Matters
Copyright, Motor Matters, 2010